Sunday 27 February 2011 14.58 EST
First published on Sunday 27 February 2011 14.58 EST

Tunisia was thrown into turmoil once more after Mohamed Ghannouchi resigned as prime minister of the post-revolution government amid further clashes between police and protestors. The interim president, Fouad Mebazaa, named the former government minister Beji Caid-Essebsi as Ghannouchi's replacement.

Ghannouchi said he felt forced to stand down "because I am not willing to be a person that takes decisions that would end up causing casualties". He made the announcement after three people died on Saturday and nine others were injured during outbreaks of violence on the streets of the capital, Tunis.

Tunisia's interim coalition has struggled to assert its authority since a wave of protests that started in December sparked what was called the "jasmine revolution", leading to the overthrow in January of president Zine el Abidine Ben Ali, who had ruled for 23 years.

Protestors have targeted Ghannouchi, accusing him of being too close to the former government. They have also become frustrated over the slow pace of change since the revolution despite the interim government's pledge to hold a general election by 15 July this year.

Ghannouchi, 69, who since 1989 had held various ministerial posts under the old regime, told a news conference he had thought carefully about the decision. "I am not running away from responsibility," he said. "This is to open the way for a new prime minister."

He added: "This resignation will serve Tunisia, and the revolution and the future of Tunisia."

On a third day of clashes, police fired tear gas and warning shots in an effort to disperse stone-throwing youths and protesters shouting anti-government slogans around Habib Bourguiba avenue in central Tunis. More than 100 people were arrested and accused of "acts of destruction and burning", according to a statement by the Tunisian interior ministry put out by the state-run news agency Tunis Afrique Presse.

Demonstrators want the interim government disbanded along with the current parliament. They also seek the suspension of the constitution and the formation of an elected assembly that can write another, organise elections and oversee the transition to democracy.

Ghannouchi took power after Ben Ali fled on 14 January. He formed a new "national unity" government, including opposition party members and a blogger.

Tunisia's revolution was sparked by the death of a young street vendor, Mohammed Bouazizi, in December. In an act of desperation which sparked unrest in several other Arab countries in the region, Bouazizi set fire to himself after officials stopped him selling vegetables without permission.